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The Long Shadow of the 1.5°C Target and the Polar Tipping Point

Tuesday, 11 November 2025 23:11

Summary

A decade after the adoption of the Paris Agreement, a new wave of scientific analysis reveals the profound chasm between global climate ambition and the reality of current emissions pathways. The latest research from the polar regions indicates that a high-emissions trajectory could render nearly 60 per cent of Antarctic ice shelves non-viable by 2300, threatening a multi-metre sea-level rise that would reshape global coastlines. Simultaneously, the geopolitical and economic friction inherent in the energy transition is becoming starkly apparent in the Global South. Nations like South Africa struggle to implement a 'Just Energy Transition' away from coal, while a surge in Chinese-backed, off-grid coal plants in Indonesia, built to power the critical mineral supply chain for electric vehicles, highlights a profound contradiction at the heart of global decarbonisation efforts. The scientific consensus underscores that the world is at a critical juncture, where the failure to meet the 1.5°C limit will trigger irreversible, catastrophic changes in planetary systems, demanding immediate and comprehensive policy shifts across all sectors.

The Tenth Anniversary of Paris

The tenth anniversary of the Paris Agreement in 2025 prompted a comprehensive expert retrospective on the progress and barriers encountered since its adoption in 20151. The agreement’s long-term temperature goal (LTTG) of limiting global warming to 1.5°C above pre-industrial levels has become the central metric for global climate action planning1,2. Governments, international agencies, and private entities have increasingly recognised the implications of this ambitious target for both near-term and long-term greenhouse gas emissions reduction strategies1. The United Nations climate change regime, now three decades old, has evolved through four key stages, culminating in the facilitative and catalytic approach embodied by the Paris Agreement3,4. This model, which relies on voluntary Nationally Determined Contributions (NDCs) rather than prescriptive, legally-binding targets, is considered by some analysts to be the approach best suited to address the intractable nature of the climate change problem3,4. However, the facilitative structure has also been criticised for allowing a significant gap to persist between national pledges and the emissions reductions required to meet the 1.5°C goal5. Developed countries are expected to take the lead by undertaking economy-wide absolute emission reduction targets, while developing countries are merely encouraged to move towards such targets over time4. The ongoing challenge remains the successful development and implementation of updated NDCs that align with the LTTG1. Furthermore, the financial instrument designed to support this transition, the Green Climate Fund (GCF), continues to be a source of tension among the parties1. The success of the entire climate regime hinges on whether the world can satisfy the Paris Agreement’s temperature limits, a necessity highlighted by the potential for multi-metre sea-level rise from the East Antarctic Ice Sheet if warming exceeds 2°C6.

The Antarctic Reckoning

The structural integrity of the Antarctic ice shelves, which act as crucial buttresses restraining the flow of inland ice into the ocean, is now understood to be far more vulnerable than previously modelled7,8. A comprehensive analysis of the effect of ocean warming on the continent’s ice shelves has delivered a stark warning about the consequences of a high-emissions future7. The study, which examined 64 Antarctic ice shelves, found that under a high-emission scenario where warming reaches nearly 12°C by 2300, a staggering 38 of those shelves, or 59 per cent, would become non-viable7. The disappearance of these shelves would potentially contribute up to 10 metres of global sea-level rise7. Ocean warming has been identified as the primary driver of this decline, accelerating the melting of the ice sheets7. The modelling suggests that the decline would accelerate from 2085 and peak around 21707. Conversely, the research underscores the urgency of pursuing low-emission pathways, as a scenario where warming is kept below 2°C by 2300 would result in only one of the 64 shelves becoming non-viable, with the risk increasing only after 22507. The East Antarctic Ice Sheet (EAIS), which holds the vast majority of the Earth’s glacier ice, equivalent to about 52 metres of sea-level rise, is often viewed as less vulnerable than the West Antarctic or Greenland ice sheets6. However, high-emissions scenarios beyond 2100 are projected to generate increased ice discharge from the EAIS, potentially leading to several metres of sea-level rise within just a few centuries6. While some regions of the EAIS have lost mass in recent decades, most projections indicate increased accumulation across the ice sheet over the twenty-first century, keeping it broadly in balance for now6. The importance of satisfying the Paris Agreement’s goal of limiting warming below 2°C is paramount to avert a multi-metre contribution to sea level from the EAIS over the next few centuries6. The complexity of the Antarctic environment is further highlighted by a controversial study suggesting that some ice shelves, particularly in East Antarctica, may be stabilising due to heightened snowfall and shifts in ocean currents introducing cooler waters9. This finding challenges previous models that predicted widespread collapse by 2100, though the overall consensus remains that many regions are perilously vulnerable9.

The Arctic's Freshwater Paradox

The Arctic Ocean, the smallest of the world’s five major oceans, plays a critical role in global climate regulation, acting as a pathway between the Pacific and Atlantic Oceans and influencing the meridional overturning circulation10,11. A significant change in this system is the freshening of the Canada basin, which began in the 1990s and continued through to at least the end of 200812. By that time, the Arctic Ocean may have gained four times the amount of fresh water that comprised the Great Salinity Anomaly of the 1970s12. This influx of fresh water raises the spectre of a slowing global ocean circulation, a critical component of the planet’s heat distribution system12. While increased sea ice melting and runoff have been cited as causes, the dominant freshwater content changes observed between 2005 and 2008 were an increase in the Canada basin balanced by a decrease in the Eurasian basin12. These changes were not primarily driven by the strength of the wind-driven Beaufort Gyre circulation, as previously thought, but rather by a cyclonic shift in the ocean pathway of Eurasian runoff12. This shift was forced by a strengthening of the west-to-east Northern Hemisphere atmospheric circulation, characterised by an increased Arctic Oscillation index12. The Arctic Ocean’s stratification is profoundly influenced by sea-ice processes, which provide a fresher surface layer upon melting and a mixing of surface waters via brine rejection upon freezing11. The cold halocline layer is particularly important, as it provides a density barrier that traps the heat stored in the Atlantic layer away from the ice11. Changes in water mass and albedo in the Arctic may affect local and global climate, including the meridional overturning circulation, which heralds challenges for various levels of the Arctic ecosystem11.

The Just Transition's Crucible: South Africa

The concept of a 'Just Energy Transition' (JET) has moved from a theoretical framework to a complex, contested national programme in South Africa, one of the world’s major greenhouse gas emitters13,14. The country has set an ambitious goal of achieving net-zero emissions by 2050, but its energy system remains overwhelmingly dependent on coal, which supplies the majority of its electricity13,15. The coal industry is fundamental to the country’s decarbonisation plans, providing jobs for more than 90,000 people15. The JET, supported by the Presidential Climate Commission (PCC), aims to transition the country towards sustainable, clean energy sources while simultaneously addressing the potential socioeconomic impact on coal-dependent communities15,16. The Mpumalanga province, the largest coal mining region, faces the most significant challenges14. Analysis suggests that the Mpumalanga economy is in danger of shrinking relative to the baseline unless the JET is managed quickly and carefully14. The transition must be people-centred, prioritising the needs of all citizens, creating new sectors for economic growth, and addressing persistent energy inequalities and the ongoing energy crisis16. The country’s climate-related policies include mechanisms for decarbonising the economy and facilitating new climate-resilient opportunities, such as the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP), which has brought over 6 GW of renewable energy capacity online since 201115,17. However, the share of renewable energy in the total mix remains small14. The challenge is compounded by the finding that South Africa may not possess the necessary resources to achieve its climate goals, with climate financing covering only a portion of the required investment13. The country’s JET model is the first of its kind globally, and its success or failure is being keenly watched as a test case for how developing nations can navigate the complex trade-offs between economic development, energy security, and climate action16.

The Nickel Boom and the Coal Contradiction in Asia

A profound contradiction in the global energy transition is unfolding in Indonesia, where a surge in Chinese-backed, off-grid coal-fired power plants is undermining international fossil fuel pledges18. This new wave of coal capacity is not primarily for the national grid but is instead built to supply electricity to Indonesia’s fast-growing nickel mining and processing sector18. Chinese investment has flowed into Indonesia’s metal mining and smelting sector to secure raw materials for electric vehicle battery makers and stainless steel production18. By the end of the decade, Indonesia is projected to supply about 44 per cent of the processed nickel used in batteries and stainless steel18. The growth of these 'captive' coal power plants, which account for 18 per cent of Indonesia’s coal capacity, is driven by the country’s economic strategy, including a 2020 ban on nickel ore exports designed to develop a local processing industry18,19. This industrial strategy, however, relies on energy-intensive refineries and smelters powered predominantly by coal20. The surge in capacity comes despite Chinese President Xi Jinping’s pledge four years prior to end official financing of overseas coal projects18. Following this announcement, newly installed coal-fired power plant capacity in Indonesia nearly tripled to more than 7 gigawatts as work wrapped up on projects already in the pipeline18. Chinese investors are involved in over 70 per cent of the captive coal power capacity, with the financing process for these off-grid plants often lacking transparency19,20. The environmental and social costs of this development are significant21. For instance, a 2x100 megawatt coal plant in Sumatra, majority-owned by a Chinese state enterprise, incurred environmental penalties in 2023 for dumping fly ash into a protected marine area21. Data from a local clinic near the plant showed a large share of young people suffering from acute respiratory infections, highlighting the direct human cost of the coal contradiction21. Decarbonising these captive coal plants is a complex technical and socioeconomic conundrum, facing a trilemma of Indonesia’s economic priorities, inadequate power grids, and limited low-carbon alternatives19.

The Hydrogen Question and the Mitigation Frontier

As the world grapples with the dual challenge of decarbonisation and energy security, hydrogen has emerged as a critical, yet complex, component of the mitigation frontier22. Specifically, 'blue hydrogen,' which is produced from natural gas with carbon capture and storage (CCS), has been scrutinised for its effective climate impacts from a life cycle perspective22. Recent research indicates that the climate impact of blue hydrogen can vary over large ranges, depending on a few key parameters22. These parameters include the methane emission rate of the natural gas supply chain, the carbon dioxide removal rate at the hydrogen production plant, and the global warming metric applied22. Methane, a potent greenhouse gas, is a significant concern, as leaks from the natural gas supply chain can undermine the climate benefits of the CCS process23. State-of-the-art reforming technology, when combined with high CO2 capture rates and a natural gas supply featuring low methane emissions, can achieve a substantial reduction in greenhouse gas emissions compared to conventional natural gas reforming or direct combustion22. Under these optimal conditions, blue hydrogen is considered compatible with low-carbon economies, exhibiting climate change impacts at the upper end of the range caused by hydrogen production from renewable-based electricity, known as 'green hydrogen'22. However, a critical finding is that neither current blue nor green hydrogen production pathways can render fully 'net-zero' hydrogen without the implementation of additional carbon dioxide removal technologies22. The development of a globally interconnected solar-wind system is also being explored as a key mitigation strategy to address future electricity demands24. Furthermore, innovative solutions, such as using building materials to store carbon dioxide, could potentially sequester more than 16 billion tonnes of CO2 annually25.

Conclusion

The scientific and geopolitical landscape of climate change in the mid-2020s is defined by a tension between existential urgency and economic inertia. The retrospective on the Paris Agreement confirms that while the 1.5°C target has successfully focused global ambition, the voluntary nature of NDCs has failed to close the emissions gap, leaving the world on a trajectory that risks catastrophic planetary shifts1,5. The latest glaciological research provides a terrifying clarity to this risk, quantifying the potential loss of nearly 60 per cent of Antarctic ice shelves under a high-emissions scenario, a tipping point that would commit the planet to multi-metre sea-level rise7. This scientific reckoning is mirrored by the complex, often contradictory, realities of the energy transition on the ground16,18. The struggle for a 'Just Energy Transition' in coal-dependent nations like South Africa highlights the immense social and financial capital required to pivot away from entrenched fossil fuel economies13,15. Simultaneously, the proliferation of new coal capacity in Indonesia, driven by the global demand for critical minerals like nickel for the electric vehicle revolution, exposes the ethical and environmental compromises being made in the name of decarbonisation18,20. The path forward demands not only technological innovation, such as the careful deployment of hydrogen and carbon removal solutions, but also a radical re-evaluation of global economic priorities22,24. The evidence is clear: the window for a managed transition is closing, and the failure to align national economic strategies with the 1.5°C limit will result in irreversible consequences for the planet’s most critical systems, from the polar ice sheets to the global ocean circulation7,12.

References

  1. Expert retrospective on a decade of the Paris Agreement

    Supports the discussion on the tenth anniversary of the Paris Agreement, the 1.5°C LTTG, NDCs, and the role of the Green Climate Fund.

  2. Expert retrospective on a decade of the Paris Agreement

    Supports the discussion on the 1.5°C long-term temperature goal (LTTG) and the reflection on the Paris Agreement's key Articles.

  3. The UN Climate Change Regime Thirty Years on: A Retrospective and Assessment

    Supports the discussion on the history and structure of the UN climate change regime, including the facilitative/catalytic model of the Paris Agreement.

  4. The UN Climate Change Regime Thirty Years on: A Retrospective and Assessment+

    Supports the details on the facilitative/catalytic model, the four stages of the regime, and the differentiation of commitments between developed and developing countries.

  5. Expert retrospective on a decade of the Paris Agreement - ResearchGate

    Supports the general discussion on the Paris Agreement's goals and the need for effective climate action.

  6. Response of the East Antarctic Ice Sheet to past and future climate change - ResearchGate

    Supports the discussion on the East Antarctic Ice Sheet's vulnerability, the 52-metre sea-level equivalent, and the multi-metre sea-level rise risk under high-emissions scenarios beyond 2100.

  7. Climate change: Antarctic ice shelves threatened by ocean warming (Nature)

    Supports the core findings on Antarctic ice shelf stability, the 59% non-viable shelves under high-emissions, the 10-metre sea-level rise potential, and ocean warming as the primary driver.

  8. Most Antarctic ice shelves are set to disappear if greenhouse-gas emissions remain high

    Supports the general finding that Antarctic ice shelves are set to disappear under high-emissions scenarios.

  9. Antarctic Ice Shelves Stabilizing? Controversial Study Challenges Collapse Predictions

    Supports the discussion of the controversial study suggesting some East Antarctic ice shelves may be stabilising due to snowfall and cooler currents.

  10. Arctic Ocean Circulation – going around at the top of the world - Polar Science Center

    Supports the description of the Arctic Ocean's size and its role as a pathway in global ocean circulation.

  11. Arctic Ocean Circulation – going around at the top of the world

    Supports the discussion on the Arctic Ocean's role in meridional overturning circulation, the influence of sea-ice on stratification, and the importance of the cold halocline layer.

  12. Changing Arctic Ocean freshwater pathways

    Supports the details on the freshening of the Canada basin, the comparison to the Great Salinity Anomaly, and the role of the Arctic Oscillation and Eurasian runoff.

  13. South Africaʼs Just Energy Transition: Issues and Prospects

    Supports the context of South Africa as a major emitter, its net-zero goal, and the finding that it may not possess the resources to achieve its climate goals.

  14. Just Energy Transition of South Africa in a Post-COVID Era

    Supports the discussion on the socioeconomic impact of the JET, the focus on Mpumalanga province, and the risk of the economy shrinking without careful management.

  15. Just energy transition in South Africa | United Nations Development Programme

    Supports the facts on coal supplying the majority of electricity, the 90,000 jobs, the role of the Presidential Climate Commission (PCC), and the REIPPPP.

  16. Whose just energy transition? A South African perspective

    Supports the argument for a people-centred approach, the need to address energy inequalities, and the status of South Africa's model as a global first.

  17. JUST ENERGY TRANSITION IN SOUTH AFRICA - Natural Justice

    Supports the fact that the REIPPPP has brought over 6 GW of renewable energy capacity online.

  18. Rise in Chinese off-grid coal plants in Indonesia belies pledge to end fossil fuel support

    Supports the core facts on the surge in Chinese-backed off-grid coal in Indonesia, the link to nickel processing for EV batteries, the undermining of China's pledge, and the projected 44% share of processed nickel.

  19. Decarbonizing captive coal power plants in Indonesia and implications for Chinese stakeholders

    Supports the fact that captive coal plants account for 18% of Indonesia's coal capacity, the involvement of Chinese investors in over 70% of capacity, and the trilemma of decarbonising these plants.

  20. Indonesia: Off-grid coal plants inside China-built industrial parks evade public scrutiny

    Supports the discussion on 'captive' or off-grid plants for industrial parks and the lack of transparency in their financing.

  21. Censured Sumatra coal plant blamed for sickening children in Indonesia's Bengkulu

    Supports the specific example of the Sumatra coal plant, the environmental penalties for dumping fly ash, and the link to acute respiratory infections in children.

  22. On the climate impacts of blue hydrogen production

    Supports the discussion on blue hydrogen, its climate impacts, the key parameters (methane, CO2 removal), and the finding that neither blue nor green hydrogen is fully 'net-zero' without additional CO2 removal.

  23. JUST ENERGY TRANSITION IN SOUTH AFRICA - Natural Justice

    Supports the fact that methane leaks from gas pipelines are a significant environmental concern, which is relevant to the blue hydrogen discussion.

  24. Mitigation | Sustainable Solutions Lab

    Supports the mention of a globally interconnected solar-wind system as a mitigation strategy.

  25. Mitigation | Sustainable Solutions Lab

    Supports the mention of building materials potentially storing more than 16 billion tonnes of CO2 annually.